Transfer RNA nucleoside composition in 13762 rat adenocarcinoma.

1. Abnormalities in patterns of tRNA methylation and in the activities of tRNA methyltransferases are well-documented phenomena. In this study, we focused our attention on tRNA from adenocarcinoma, a 9,10-dimethyl-1,2-benzanthracene-induced mammary tumor, because prior evidence has suggested the occurrence of an abnormal pattern of tRNA methylation. 2. Chemical postlabeling of tumor vs normal rat liver and mammary gland tRNAs revealed tumor specific differences in the modified nucleoside distribution, i.e., a 5.8-fold increase in tumor N-2-methylguanosine together with a 2.7-, 2.8-, 2.6- and 2.8-fold decrease in tumor 1-methyladenosine, dihydrouridine, pseudouridine and 5-methylcytidyne, respectively. 3. Class A tRNAs, a slower gel migrating group of tumor tRNAs, exhibited even lower 1-methyladenosine levels. Most of the remaining nucleosides in class A tRNAs showed molar ratios similar to those found in bulk tumor tRNA. However, N-2-methylguanosine levels in class A tRNA are intermediate between bulk tumor tRNA (2.8%) and mammary gland tRNA (0.49%). 4. The only qualitative difference found in tumor tRNA seems to be the absence of inosine usually present in tRNAs from liver and mammary tissues. 5. In spite of its abnormal methylation pattern adenocarcinoma tRNA binds to glucocorticoid receptor protein from mouse AtT-20 cells, generating a 6S tRNA-protein complex, in a fashion similar to that previously described for the endogenous tRNA isolated from the same cells.

Transfer RNA nucleoside composition in 13762 rat adenocarcinoma

Abnormalities in patterns of RNA methylation and in the activities of tRNA methyltransferases are well-documented phenomena. In this study, we focused our attention on tRNA from adenocarcinoma, a 9,10-dimethyl-1,2-benznthracene-induced mammary tumor, because prior evidence has suggested the occurence of an abnormal pattern of tRNA methylation. Chemical postlabeling of tumor vs normal rat liver and mammary gland tRNAs revealed tumor specific differences in the modified nucleoside distribution, i.e., a 5.8-fold increase in tumor n-2-methylguanosine together with a 2.7-,2.8-,2.6-, and 2.8-fold decrease in tumor 1-methyladenosine, dihydrouridine, pseudoridine and 5-methylcytidyne, respectively. Class A tRNAs, a slower gel migrating group of tumor tRNAs, exhibited even lower 1-methyladenosine levels. Most of the remaining nucleosides in class A tRNAs showed molar ratios similar to those found in bulk tumor tRNA. However, N-2-methylguanosine levels class A tRNA are intermediate between bulk tumor tRNA (2.8%) and mammary gland tRNA (0.49%). The only qualitative difference found in tumor tRNA seems to be the absence of inosine usually present in tRNAs from liver and mammary tissues. In spite of its abnormal methylation pattern adenocarcinoma tRNA binds to glucocorticoid receptor protein from mouse AtT-20 cells, generating a 65 tRNA-protein complex, in a fashion similar to that previously described for the endogenous tRNA isolated from the same cells

Leiomyosarcoma of the inferior vena cava: angiographic and computed tomography findings. Report of two cases and review of imaging criteria.

Leiomyosarcoma, a highly malignant tumor of the inferior vena cava, is rare. Only 55 cases have been reported in the world literature, and of these only 18 were evaluated with a special vascular procedure, either arteriography or inferior vena cavography. In two cases of leiomyosarcoma of the inferior vena cava, we performed arteriography and inferior vena cavography. In one, computed tomographic studies were also carried out. Cavography showed a lobulated filling defect in one case and complete caval occlusion with collateral circulation in the other. In the one case in which it was performed, computed tomography clearly demonstrated the tumor's size and its relationship to surrounding organs. Arteriographic studies, however, allowed only an indistinct delineation of the extent of tumor growth in one case. Venography followed by computed tomography should permit adequate assessment of most leiomyosarcomas of the inferior vena cava, with arteriography reserved for tumors involving the upper cava in which hepatic involvement must be evaluated.